1. Field of the Invention
The present invention relates to a water producing apparatus for producing liquid water from moisture in air.
2. Description of the Prior Arts
A water producing apparatus for producing a desalted water from sea water has been well-known as an apparatus for converting sea water into a desalted water. A water treating apparatus for treating a waste water such as a drainage in high degree to obtain water having high clarity has been proposed. This is one of the water producing apparatus classified in the apparatus for converting sea water into a desalted water. These apparatuses require a solution containing liquid water as a main component for producing water. Thus, these water producing apparatus could not be used to produce water in a place where no liquid water is found such as desert since the liquid water is used as the source.
It has been required to provide a water producing apparatus for producing water even in a place where no liquid water is found. Such novel water producing apparatus has been developed.
The novel water producing apparatus is an apparatus for producing water from a moisture in the air and is a novel water producing apparatus which can produce water in any place as far as the air is present. Of course, it is impossible to produce water if no moisture is present in the air. According to the statistical data for weather and the results of inventors' studies, even in the air in a large desert such as the central part of the Arabian desert, 3 to 4 g. of water is included in 1 m.sup.3 of the air, and accordingly, water can be produced. Thus, water can be obtained in a sterile land to live and to work and water can be used for irrigation to culture plants. The water producing apparatus contributes to expand living zones for human-being and is quite important.
The principle of the water producing apparatus is to produce water by adsorbing moisture in the air in an adsorbent as the first step and then, desorbing water adsorbed as steam by heating the water-logged adsorbent and condensing the steam in a condenser as the second step. The adsorbent is dehydrated to regenerate the adsorbing function whereby the adsorbent can be repeatedly used for adsorbing moisture in air. Thus, liquid water can be repeatedly obtained from air.
FIG. 1 is a diagram for showing the principle of the apparatus for producing liquid water from moisture in the air by using an adsorbent.
In FIG. 1, the reference numeral (1) designates a column for holding an adsorbent (1a); (2) and (3) respectively designate blowers; (4) designate a condenser for condensing a hot air having high humidity desorbed from the column (1) in the desorbing step; (4a) designates an air cooling fan; (5) designates a heater for heating the air fed through the blower (3), by a burner (5a); (6) designates an air-open type water receiver which stores water obtained by the condensation; (6a) designates water produced; (7) designates a discharge passage for discharging dried air fed from the column (1) after adsorbing moisture in the adsorbing step as the first step; (7a) designates a sucking passage for feeding the air into the column (1); (8) designates a passage for feeding steam desorbed from the column (1) in the desorbing step; (8a) designates a passage for recycling, to the column (1), the gas (steam) for the desorption by the blower (3) while heating it by the heater; (8b) designates a passage for feeding the steam for an increased volume of the steam desorbed by the column (1) into the condenser (4); (8c) designates a passage for discharging the liquid water condensed by the condenser (4) into the water receiver (6); (9), (10), (11) and (12) respectively are valves for opening and closing the passages which are placed in the passages for feeding the air, the dried air and the hot air having high humidity.
The operation of the present invention will be illustrated.
As the adsorbing step (the first step) for adsorbing moisture in the air on the adsorbent (1a) held in the column (1), the valve (9) and the valve (10) are opened and the blower (2) is driven to feed the air into the column (1). The moisture in the air is adsorbed on the adsorbent (1a) and the dried air is discharged from the column (1) through the valve (9). When the adsorbent (1a) adsorbs enough moisture, the adsorbing step is finished. Then, the desorbing step for desorbing water adsorbed on the adsorbent (1a) is carried out. The valves (9) and (10) are closed and then the valves (11) and (12) are opened.
In the desorbing step, the blower (3), the heater (5) and the condenser (4) are mainly used. That is, the gas in the column (1) and the recycling passage (8), (8a) is recycled by the blower (4). The gas is heated by the heater (5). The hot gas (about 300.degree. C. in the case of silica gel as the adsorbent) is fed into the column (1) whereby the adsorbent (1a) is heated to desorb the adsorbed water as steam. The temperature of the hot air fed from the heater (5) is decreased by the latent heat for desorption. When silica gel is used as the adsorbent (1a), it is preferable to be about 200.degree. C. be the temperature of hot air having high humidity discharged from the column (1). The temperature depends upon the desorption of the adsorbed water.
The gas recycled by the blower (3) is air remained in the column (1) at the initiation of the desorbing step. During the desorption, the air is replaced by the steam formed by the desorption and only the steam is substantially remained for a short time. The steam corresponding to the desorbed steam formed by the desorption is discharged through the passage (8b) into the condenser (4) and is condensed into the liquid water in the condenser and is fed through the passage (8c) into the water receiver (6). The end of the passage (8c) is opened through the water receiver (6) and accordingly, the pressure for the recycling gas for the desorption is substantially the atmospheric pressure (slightly higher than the atmospheric pressure for the pressure loss in the condenser (4). The temperature of the recycling gas (steam) for the desorption is about 200.degree. to 300.degree. C. and accordingly, the steam is super heated steam. The heat for the adsorbent (1a) in the column (1) is given by the non-latent heat of the steam. The recycling steam is not condensed into a liquid water by transferring the heat to the adsorbent (1a). The desorbing step is continued until completing the desorption of the water from the adsorbent (1a). After completing the desorbing step, the blower (3), the heater (5) and the condenser (4) are stopped and the valves (11), (12) are closed and then, the adsorbing step is carried out. The adsorbing step and the desorbing step are repeated to obtain the liquid water in the water receiver (6).
In the case of the water producing apparatus. There is a question whether the water adsorbed in the adsorbent can be fully desorbed as steam by the steam. However, this is not a problem. The desorption is performed by the high temperature and it is balanced to the partial pressure of the steam around the adsorbent. The partial pressure of the steam is about 1 atm. (the atmospheric pressure) and does not exceed the limit. Therefore, the temperature of the adsorbent can be high enough to balance to 1 atm. When the temperature of the adsorbent is 300.degree. to 200.degree. C., the water can be desorbed to remain only 3 to 4 wt.% of water even though the partial pressure of the steam is 1 atm. In the adsorbing step, the water is usually adsorbed for 10 to 20 wt.% based on the silica gel depending upon the condition of a humidity and a temperature. On the other hand, the adsorbent can be heated by any hot gas. In this case, the steam is used for heating the adsorbent.
In the apparatus in the prior invention, in order to condense the desorbed steam into the liquid water, the condenser has been cooled by the air cooling, and accordingly, the latent heat in the condensation of the steam is lost in the atmosphere. Nevertheless, the energy for driving the blower for the air cooling is required. This is a serious problem from the viewpoint of the saving of energy.
Therefore, a water producing apparatus for producing the liquid water with a smaller energy without energy loss.